There's no reason you can't make the inductor variable instead of the
capacitor -- as long as it has some way of making a variable tap. With
the method I described, you have to be able to adjust both the tank's
resonant frequency and the tap in order to assure getting a match.

Roy Lewallen, W7EL

Airy R. Bean wrote:

Presumably the roller coaster could be used for
a vari-tap, but then that means that the whole coil
will always be in circuit.

Time for a quikc .XLS for all bands.....